So, you are saying it leaks down slowly? If so then it would be best to find the leak and repair it. Make sure the bags are aired up and then use soapy water in a squirt bottle on every air line connection. The bubbles tell the story.
TV1: Black Sheep, 2001 Dodge 3500, 800,xxx miles, a few non-stock parts here and there...
TV2: Brownie, 1989 Dodge W250, only 256,000 miles!
TV3: 2004.5 Dodge 3500, 415,000 miles, 6 spd
TV4: 2005 Dodge 3500, 478,000 miles, 4spd auto
"Too much of what I once knew I now know not" Me